3 Answers
3

Edit: On second thought, I realized that I may have misunderstood the question. If you want the directory to only be visible to a specific user (i.e. for every other user, that list doesn't even show up in the directory listing), you can't do that without prohibiting other users from listing the contents of the parent directory. So if the directory is /foo/bar then you can remove the x permission on /foo (for everyone but the owner) preventing other users from listing the contents of /foo, but you can't hide /foo/bar specifically (though you can certainly hide its contents).

Old answer:

Make that specific user the owner of the directory and then remove all permissions on that directory for everyone but the owner. In the shell, you'd use chmod to do this:

chmod 700 the_directory

If you're using a filemanager, just remove all the checkmarks in the permissions-tab except the ones in the "User"-column (the exact details depend on the filemanager of course).